[Fix] parameter_types! dead code errors (paritytech#12340)

* [Fix] parameter_types! dead code errors

* mark the whole impl allow(unused)

frame/support/src/lib.rs

@@ -361,9 +361,9 @@ macro_rules! parameter_types {
  }
  };
  (IMPL_STORAGE $name:ident, $type:ty, $value:expr $(, $ty_params:ident)*) => {
+ #[allow(unused)]
  impl< $($ty_params),* > $name< $($ty_params),* > {
  /// Returns the key for this parameter type.
- #[allow(unused)]
  pub fn key() -> [u8; 16] {
  $crate::sp_core_hashing_proc_macro::twox_128!(b":", $name, b":")
  }
@@ -372,7 +372,6 @@ macro_rules! parameter_types {
  ///
  /// This needs to be executed in an externalities provided
  /// environment.
- #[allow(unused)]
  pub fn set(value: &$type) {
  $crate::storage::unhashed::put(&Self::key(), value);
  }
@@ -448,6 +447,7 @@ macro_rules! parameter_types_impl_thread_local {
  }
 
  /// Mutate the internal value in place.
+ #[allow(unused)]
  pub fn mutate<R, F: FnOnce(&mut $type) -> R>(mutate: F) -> R{
  let mut current = Self::get();
  let result = mutate(&mut current);
@@ -456,6 +456,7 @@ macro_rules! parameter_types_impl_thread_local {
  }
 
  /// Get current value and replace with initial value of the parameter type.
+ #[allow(unused)]
  pub fn take() -> $type {
  let current = Self::get();
  Self::set($value);